Lubricants containing polymeric additives



United States Patent 3,372,120 LUBRICANTS CONTAINING POLYMERIC ADDITIVES Lester E. Coleman, Cleveland, Ohio, assignor to The Lubrizol Corporation, Wickliife, Ohio, a corporation of Ohio No Drawing. Continuation-impart of application Ser. No. 90,630, Feb. 21, 1961. This application May 15, 1967, Ser. No. 638,612

19 Claims. (Cl. 25251.5)

ABSTRACT OF THE DISCLOSURE Oils containing interpolymers of N-vinyl oxazolidones have improved viscosity-index properties, pour point properties, dispersancy properties, and resistance to the formation of insoluble degradation products. At least one oilsolubilizing vinyl co-monomer is required in the preparation of the interpolymers used in this invention. Additional oil-solubilizing vinyl co-monomers or other comonomers may be used in making these interpolyniers.

This is a continuation-in-part of copending application Ser. No. 90,630, filed Feb. 21, 1961 and now abandoned.

This invention relates to compositions which are resistant to the deposition of degradation products. In a more particular sense it relates to such compositions which contain small amounts of a polymeric material which latter material imparts to the composition the property of inhibiting the settling out of such degrada tion products. The invention contemplates a wide range of such materials, e.g., hydrocarbon oils such as light and heavy fuel oils, cutting oils, hydraulic fluids and lubricating oils, and synthetic oils, such as are used as lubricants and hydraulic fluids.

Hydrocarbon oils are used in many environments and in almost all cases are subject to chemical change such that solid products are formed. These solid products settle out ultimately to form sludge or varnish and such settling out inevitably poses problems for the further satisfactory use of the hydrocarbon oil. If it is being used as a fuel then the insoluble material which has settled out will tend to cause problems by clogging the various strainers, screens, filters, transmission lines, burner tips, etc. of the equipment in which it is being used. The accumulation of such deposits likewise will prove troublesome in the case of a lubricating oil, so that it is important to prevent the separation of such solid materials from hydrocarbon compositions used for these purposes.

This problem has been approached by attempting to prevent the formation of these degradation products and also by attempting to keep the degradation products dispersed in the oil as they are formed. Both of these approaches have been successful to a certain extent, but the problem still is susceptible to an improved solution.

The attempts to disperse the solid degradation products as they are formed has in the past been solved by the use of metal-containing detergents. These are principally the alkaline earth metal sulfonates. The most effective of these metal sulfonates have been those which contain stoichiometrically excessive amounts of metal, i.e., an amount of metal in combined form (usually the oxide or carbonate) in excess of that which is equivalent to the sulfonate group. It is presumed that this excess metal is itself dispersed by the metal sulfonate and that the dispersed metal, ordinarily insoluble in oil itself, is effective to disperse foreign contaminants present in the oil.

An important disadvantage of such metal sulfonates, i.e., those which contain an excessive amount of metal, is that the excess metal-confining constituent of such addi- 3,372,120 Patented Mar. 5, 1968 tives is itself ordinarily insoluble in oil and thus may be in itself 'a source of considerable deposit-forming material. Quite obviously in approaching a problem having to do with the deposition of degradation products, it is important to consider the composition of additives to ascertain whether or not such additives might not themselves contribute to the very problem which they are intended to solve. In this sense an additive which is intended to act as a dispersant of degradation products might advantageously contain no metal at all. Such an additive would contribute no ash to a lubricant and is generally referred to in the art as an ashless degergent.

It is accordingly an object of the present invention to provide improved additives for fuels and lubricants.

It is a further object of this invention to provide improved fuel oil compositions.

Still another object of this invention is to provide improved lubricant compositions.

These and other objects are achieved by providing a composition comprising a major proportion of an oil selected from the class consisting of fuels and lubricating oils and at least 0.0001% by weight of an interpolymer having monomeric units of from about 5 to about 25 parts by weight of an N-vinyl oxazolidone and from about 100 to about parts by weight of at least one oil-solubilizing vinyl co-monomer.

The N-vinyl oxazolidone materials which may be used as indicated above have the structure where R is selected from the group consisting of hydrogen and a lower alkyl group and R and R are radicals having fewer than seven carbon atoms, selected from the group consisting of hydrogen, phenyl, chloroalkyl and alkyl. The preferred material, however, is the unsubstituted N-vinyl oxazolidone, or the S-methyl substituted homolog viz, that which conforms to the above structure and in which R and R are hydrogen, and R is hydrogen or methyl.

The unsubstituted N-vinyl oxazolidone may be prepared by reaction of diethanolamine with diethyl carbonate to yield the N-(fi-hydroxyethyl)-oxazolidone according to the equation below:

co I

The above product may then be treated with thionyl chloride to give the B-chloroethyl derivative which in turn is dehydrochlorinated to give the N-vinyl oxazolidone. This method of preparation is described in US. 2,818,362.

Alternatively the N-vinyl oxazolidone may be prepared by reaction of urea with ethylene oxide as indicated below:

wherein R is hydrogen. R may also be aryl or alkyl, often a lower alkyl having up to about 3 carbon atoms such as methyl, ethyl, propyl, etc. Further reaction of the oxazolidone product above witha vinyl ether results in transfer of the vinyl group to the nitrogen of the oxazolidone with the formation of the expected N-vinyl oxazolidone. If the vinyl group of the vinyl ether reactant is substituted in the alpha position then of course this substituent will remain and appear as an OL-SUbStltllied vinyl group in the oxazolidone product.

It will be noted that the unsubstituted N-vinyl oxazolidone may be prepared by either of the methods above whereas the substituted monomers must be prepared by the second method. This latter method is disclosed in US. 2,919,279; 2,905,690; 2,826,587; 2,891,058; and J. Org. Chem., 22, 166 (1957).

It will be noted that the introduction of organic groups into the 4- and 5-position of the oxazolidone ring may be accomplished by a suitable choice of the epoxy reactant used in preparing this ring structure. Thus the use of styrene oxide in this reaction yields 4-.pl1enyloxazolidone; the use of epichlorohydrin yields 4-chloromethyl oxazolidone; the use of 2,3-epoxy butane yields 4,5-dimethyloxazolidone.

The preferred embodiments of the invention involve the use of an unsubstituted N-vinyl oxazolidone or a 5- methyl-N-vinyl oxazolidone to prepare the interpolymer. In many instances there are advantages attending the use of an N-vinyl oxazolidone which contains lower alkyl substituents in one, two or all of the alpha, 4- and 5- positions. Substitution in the 4- and/ or 5-position is preferred. Illustrative examples of such monomers which are especially suitable for use in the invention include 4- methyl N-vinyl oxazolidone, S-ethyl N-vinyl oxazolidone, S-methyl N-vinyl oxazolidone, 4-propyl N-vinyl oxazolidone and N-isopropenyl oxazolidone.

The co-monomers used in the preparation of the interpolymer of this invention are selected from the class consisting of polymerizable vinyl monomers. This class includes esters of unsaturated alcohols (monohydric or polyhydric), esters of unsaturated acids, vinyl-substituted cyclic compounds, unsaturated acids, unsaturated ethers, unsaturated amides, unsaturated ketones, unsaturated aliphatic hydrocarbons, unsaturated acid anhydrides, and unsaturated nitriles. Specific illustrations of such monomers are: allyl, methallyl, vinyl, alpha-methyl-vinyl, 1- phenallyl esters of saturated acids such as, for instance, acetic, propionic, butyric, valeric, caproic, stearic, benzoic, phenylacetic, etc.; methyl, ethyl, propyl, isopropyl, butyl, octafluoroamyl, isobutyl, sec-butyl, tert-butyl, 2-e-thylhexyl, tetrafluoropropyl, hexadecafiuorononyl, cyclohexyl, dodecyl, tetradecyl, octadecyl, behenyl, etc., esters of unsaturated aliphatic monobasic and polybasic acids such as for instance aorylic (including alpha-substituted acrylic such as haloacrylic, alkacrylic and arylacrylic, e.g., methacrylic, ethacrylic, propacrylic, phenylacrylic, chloroacrylic, etc.), crotonic, fumaric, maleic, itaconic, citraconic, mesaconic, aconitic, methylene malonic, etc.; esters of unsaturated polyhydric alcohols (cg. butenediol) with saturated acids, representatives of which are listed above; and other co-monomers such as styrene, o-, m-, p-chloro-, fluoro-, methyl-, ethyl-, cyano-, styrenes, di-, tri-, tetra-, etc., -methyl, -ethyl, -styrenes, vinyl naphthalene, vinyl cyclohexane, vinyl furan, vinyl pyridine, vinyl benzofuran, allyl benzene, N-vinyl carbazole, N-vinyl pyrrolidone, methyl vinyl ether, ethyl vinyl ether, cyclohexyl vinyl ether, octyl vinyl ether, allyl ethyl ether, ethyl methallyl ether, methyl vinyl ketone, ethyl vinyl ketone, acrylamide, N-methyl-, N-butyl-, N-octyl-, N-nonyl-, N-dodecyl-, etc., -acrylamides, N-3-oxohydrocarbon-substituted acrylamides, such as N-l,l-dimethyl-3-oxobutyl acrylamide, N-LZ-dimethyl-l-ethyl-3-oxobutyl acrylamide, N- (l,3 diphenyl-l-methyl-3-oxopropyl)acrylamide, N-(lmethyl-1-phenyl-3-oxobutyl)methacrylamide, etc., octene- 1, dodecene-l, tetradecene-l, octadecene-l, acrylic acid, methacrylic acid, propacrylic acid, and other unsaturated aliphatic monobasic acids.

The interpolymers of this invention include copolymers, terpolymers and polymers of four or more co-rnonomers. The relative proportions of the N-vinyl oxazolidones and the vinyl co-monomers to be used in the interpolymerization depend upon the reactivity of these monomers as well as the properties of oil solubility, dispersancy, viscosity-index improving capacity, pour-point depressant quality, solubility in synthetic lubricants, etc. Interpolymers having a high degree of solubility in a hydrocarbon oil are those in which there is a relatively high proportion of an oil-solubilizing monomer, i.e. one having at least about 8 aliphatic carbon atoms. At least about 50% (by weight), preferably about of the interpolymer should consist of oilsolubilizing monomers.

In some instances the interpolymer may contain two of more different oil-solubilizing groups, i.e. groups derived from different oil-solubilizing co-monomers of the types illustrated below. Not all of the vinyl co-monomeric units in the interpolymers of this invention need be of oilsolubilizing. The proportion of the non-oil-solubilizing co-monomer varies, of course, according to the functional groups present and the size and structure of the hydrocarbon radical.

The amounts of the various monomeric units in the interpolymer depend also, to a great degree, upon the nature of the oil-solubilizing group. In an interpolymer containing 5 parts by weight of an N-vinyl oxazolidone there must be from about to about 75 parts by weight of an oil-soluble co-monomer or a mixture of oilsolubilizing co-monomers where two or more such comonomers are present and may be up to about 100 parts of the non-oil-solubilizing co-monomer or co-monomers.

(Io-monomers which lend oil solubility to an interpolymer are those illustrated above which contain an oilsolubilizing group, i.e. a hydrocarbon group having at least about seven aliphatic carbon atoms. Such oilsolubilizing groups usually contain up to about 200 aliphatic carbon atoms. Especially preferred are the following:

(1) Alkyl acrylates in which the alkyl group contains from about 8 to about 30 carbon atoms and the acrylic radical contains from 3 to about 6 carbon atoms. Decyl acrylate and decyl rnethacrylate are among the preferred monomers of this type.

(2) Dialkyl esters of one-unsaturated dicarboxylic acids in which each alkyl group contains from about 4 to about 20 carbon atoms and the acid radical contains from 4 to 5 carbon atoms. The esters of fumaric acid prepared from the mixture of alcohols derived from coconut oil serve the purpose well. Different fractions of the alcohols may be used, e.g. a 10 carbon alcohol or a fraction consisting mostly of 12 to 14 carbon alcohols, or one in which 14 to 18 carbon alcohols predominate, may be utilized in the fumarate esters in this invention. The dialkyl esters of itaconic acid are also well-suited for purposes of this invention. When the alkyl groups are butyl groups the proportion of the monomer must be higher than when the alkyl groups are derived from higher alcohols to achieve the same degree of oil solubility for the interpolymer.

(3) l-olefins having from about 8 to about 20 carbon atoms are likewise contemplated. Mixtures of l-olefins, e.g. broad distillation fractions containing C -C olefins and C -C olefins, are preferred. These preferably account for up to about 30 parts by weight of an interpolymer containing 5 parts by weight of an N-vinyl oxazolidone.

(4) Vinyl octanoate, vinyl oleate, vinyl laurate, vinyl palmitate, vinyl myristate, vinyl stearate, and other esters of this type having up to about 30 carbon atoms in the fatty acid radical and from 2 to 3 carbon atoms in the alcohol residue, (e.g. vinyl and a-methylvinyl) may account for from about 2.5 to about 20 parts by weight of an interpolymer containing 5 parts by weight of an N-vinyl oxazolidone.

(5) N-alkyl acrylamides having from about 7 to about 15 carbon atoms in the alkyl group. The lower members of the preferred group (e.g. N-heptyl acrylamide) may be incorporated in the interpolymer in a ratio of up to about 20 parts by weight for each 5 parts by weight of an N-vinyl oxazolidone. The amount of a higher N-alkyl acrylamide (e.g., N-nonyl, N-tetrapropenyl) in the interpolymer of this invention may be as much as 40 parts by weight for each parts by weight of an N-vinyl oxazolidone.

Co-monomers which do not lend oil solubility to the interpolymer are those illustrated above which do not have any group containing more than six aliphatic carbon atoms. Preferred co-monomers of this type are the following: (1) Members of the n p-unsaturated nitrile class of compounds having 3 to 4 carbon atoms. These may be used in amounts up to about 2 parts by weight per 5 parts by the Weight of an N-vinyl oxazolidone in an interpolymer of this invention. (2) Alkyl vinyl ethers having from 1 to about 6 carbon atoms in the alkyl group. These may account for as much as 20 parts by weight in an interpolymer of this invention containing 5 parts by weight of an N-vinyl oxazolidone. (3) Acrylate esters derived from perfluoroalkanols. The fiuoroalkyl acrylate: are represented by the formula late, dodecafiuoroheptyl methacrylate, etc. are some of the co-monomers of this class. They are used in amounts up to about 5 parts by weight of an interpolymer contain ing 5 parts by weight of an N-vinyl oxazolidone.

The polymerization reaction by which the interpolymers of this invention may be prepared is effected simply by subjecting a mixture of the N-vinyl oxazolidone and cornonorner(s) to conditions conducive to addition polymerization. Interpolymers formed by graft polymerization and block polymerization are also used in this invention. The polymerization may be carried out in bulk, emulsion, dispersion or solution. The method most commonly used involves contacting a solution of the monomers with a suitable addition polymerization initiator at a temperature between about 25 C. and about 150 C. The initiator may be any of the commonly employed catalysts such as potassium persulfate, cumene hydroperoxide, hydrogen peroxide, tertiarybutyl peroxide, ultra-violet light, u,a'- azodiisobutyronitrile and benzoyl peroxide.

The concentration of the catalyst is relatively small, e.g., from about 1 part of catalyst per 1,000 parts of the polymerizable mixture to about 3 to 4 parts of catalyst per 100 parts of polymerizable mixture.

The polymerization reaction by which the interpolymers of this invention are prepared is exothermic. For this reason it is best to carry it out in a solvent so as to allow some control over the temperature of the reaction mixture. An especially useful solvent for such purpose is benzene; naphtha, hexane, white oil and water may be employed with satisfaction. Sometimes it is necessary to apply external cooling or heating to the polymerization mixture to maintain a constant, desired temperature.

The preparation of the interpolymers of the lubricants and fuels of this invention is illustrated by the following examples.

Example 1 A solution of 80 grams of decyl acrylate and 20 grams of N-vinyl oxazolidone in 50 grams of benzene is purged with nitrogen gas for one hour, mixed with 0.1 gram of a,a -HZOdllSObUtYI'OIlltI'llC, and maintained at 6070 C. for 12 hours. The resulting solution containing the polymeric product is mixed with 0.1 gram of tertiary-butyl catechol (to destroy any unused initiator) and 200 grams of white oil. The solution is heated at 80 C./30 mm. Hg to distill off benzene. The residual polymer-oil solution is found to have a nitrogen content of 0.8%, indicating a weight ratio of 80:20 for decyl acrylatezN-vinyl oxazolidone in the polymer. The intrinsic viscosity of the polymer is found to be 0.65.

6 Example 2 The procedure of Example 1 is repeated except that the monomer mixture used consists of grams of dodecyl methacrylate and 15 grams of N-vinyl oxazolidine. The final polymer-oil solution is found to have a nitrogen content of 0.5%, indicating a Weight ratio of 87:13 for dodecyl methacrylatezN-vinyl oxazolidone in the polymer. The intrinsic viscosity of the polymer is 0.95.

Example 3 The procedure of Example 1 is repeated except that the monomer mixture used consists of 90 grams of dodecyl methcarylate and 10 grams of N-vinyl oxazolidone. The final polymer-oil solution has a nitrogen content of 0.31% indicating a weight ratio of 92:8 for dodecyl methacrylatezN-vinyl oxazolidone in the polymer. The intrinsic viscosity of the polymer is 0.75.

Example 4 The procedure of Example 1 is repeated except that the monomer mixture consists of 90 grams of decyl methacrylate and 10 grams of N-vinyl oxazolidone. The polymer-oil solution is found to contain 0.37% nitrogen, indicating a Weight ratio of 91:9 for decyl methacrylatezN- vinyl oxazolidone in the polymer. The intrinsic viscosity is found to be 075.

Example 5 The procedure of Example 1 is repeated except that the monomer mixture consists of 95 grams of decyl methacrylate and 5 grams of N-vinyl oxazolidone. The polymeroil solution is found to have a nitrogen content of 0.19%, indicating a weight ratio of 95:5 for decyl methacrylate: N-vinyl oxazolidone in the polymer. The polymer is found to have an intrinsic viscosity of 1.15.

Example 6 The procedure of Example 1 is repeated except that the monomer mixture used consists of 95 grams of dodecyl methacrylate and 5 grams of N-vinyl oxazolidone. The polymer-oil solution is found to have a nitrogen content of 0.22%, indicating a weight ratio of 95:5 for dodecyl methacrylate:N-vinyl oxazolidone. The intrinsic viscosity of the polymer is found to be 0.65.

Example 7 A solution of 60 grams of behenyl methacrylate and 20 grams of N-vinyl oxazolidone in 40 grams of white oil is purged with nitrogen for 0.5 hour, then mixed with 1.2 grams of benzoyl peroxide and maintained at 60-65" C. for 12 hours. The solution containing the polymeric product is diluted with grams of white oil and the final solution found to have a nitrogen content of 0.88%, indicating a weight ratio of 78:22 for behenyl methacrylatezN-vinyl oxazolidone in the polymer.

Example 8 A solution of 45 grams of behenyl methacrylate, 5 grams of N-vinyl oxazolidone, 50 grams of white oil and 0.75 gram of benzoyl peroxide is maintained at 65-75 C. for 12 hours, then mixed with 0.1 gram of tertiarybutyl catechol and diluted with 50 grams of white oil. The solution containing the polymeric product is found to have a nitrogen content of 0.36%, indicating a weight ratio of 91:9 for behenyl methacrylatezN-vinyl oxazolidone in the polymer.

Example 9 To a solution of 85 grams of decyl methacrylate and 15 grams of N-vinyl oxazolidone in 50 grams of benzene there is added 0.4 gram of a,a'-azodiisobutyronitrile and the resulting mixture heated at 65-75 C. for 22 hours.

' The resulting polymeric solution is found (after treatment with 0.1 gram of tertiary-butyl catechol) to have a nitrogen content of 0.52% and an intrinsic viscosity of 0.5.

7 Example 10 A mixture of 850 grams of decyl methacrylate, 100 grams of N-vinyl oxazolidone, 50 grams of vinyl acetate and 2000 grams of white oil is purged with nitrogen gas and then 3 grams of a,e'-azodiisobutyronitrile is added. The mixture is stirred under a nitrogen atmosphere for 20 hours at 5070 C. The resultant viscous solution is the terpolymer.

Example 11 A mixture of 237 grams of the fumarate ester of a mixture of C -C alcohols, 11.3 grams of N-vinyl oxazalidone and 72 grams of C C a-olefins is stirred under a nitrogen atmosphere while being heated to 40 C. Then, 1.6 grams of azodiisobutyronitrile is added and the mixture is heated to 50 C. Polymerization is observed after about 1.5 hours at 5060 C. After 12 hours at 50-60 C. the viscous mixture is heated to 160 C. at 15 mm. pressure and held there for 0.5 hour. About 25 grams of distillate is recovered. The residue is a terpolymer containing 0.53% nitrogen.

Example 12 A mixture of 28.8 grams of ethyl vinyl ether, 237 grams of the fumarate ester of a mixture of C C alcohols, 11.3 grams of N-vinyl oxazolidone and 1.3 grams of azodiisobutyronitrile is held within the 6070 C. range for 4 hours. Toluene is added to reduce the viscosity and the solution is held within the 6070 C. range for another 6 hours. The solution is then heated to 130 C. at 40 mm. pressure. The residue is the terpolymer.

Example 13 Nitrogen is bubbled through a solution of 800 grams of decyl methacrylate, 100 grams of N-vinyl oxazolidone, 100 grams of dibutyl itaconate and 2000 grams of white oil at room temperature. Two grams of azodiisobutyronitrile is added and the mixture is held within the range of 5060 C. for 12 hours. After an additional 1 gram of the initiator is added the temperature is maintained between 5060 C. for another 8 hours. The product contains 0.42% nitrogen.

Example 14 A solution of 26.3 grams of the fumarate ester of a mixture of C C alcohols, 5.2 grams of N-vinyl oxazolidone, 8.5 grams of Z-ethylhexyl acrylate and 40 grams of benzene is mixed with 0.2 gram of azodiisobutyronitrile under an atmosphere of nitrogen. The solution is kept in a 60 C. constant temperature bath for 65 hours. The terpolymer is precipitated in methanol, washed with methanol and dried.

Example 15 A solution of propylene tetramer (3696 grams) and acrylonitrile (1060 grams) is cooled to 8 C. and then 2200 grams of 98% H SO is added over a 2-hour period as the temperature is held within the 815 C. range. The reaction mixture is allowed to stand at room temperature overnight before pouring it into six liters of cold water. The organic layer is wwashed, extracted with benzene, dried, inhibited with 4-t-butylpyrocatechol and stripped of benzene before being distilled. The fraction boiling between 115-131 C. at 0.30.8 mm. pressure is N-tetrapropenyl acrylamide.

Twenty grams of this acrylamide, 20 grams of vinyl stearate, 2.5 grams of N-vinyl oxazolidone, 50 grams of benzene and 0.1 gram of azodiisobutyronitrile are mixed under a nitrogen atmosphere at 5080 C. to form an interpolymer.

Example 16 A sample of N(tertnonyl) acrylamide is prepared in a manner similar to that described in Example 15 for the preparation of N-tetrapropenyl acrylamide. The nonyl acrylamide distills at 1071l2 C. at 0.2-0.5 mm. pressure.

A solution of 35 grams of the above described N- (tert-nonyl) acrylamide, grams of N-vinyl oxazolidone,

5 grams of decyl acrylate, 50 grams of benzene and 0.2 gram of benzoyl peroxide is purged with nitrogen for 30 minutes at room temperature. The temperature is then raised to 5560 C. before a solution of 40 grams of the acrylamide, 10 grams of decyl acrylate and 0.2 gram of benzoyl peroxide in 50 grams of benzene is added over a period of 5 hours. After a total of 10 hours of reaction time the terpolymer is precipitated from a benzene solution twice by adding methanol. The dried product con tains 6.10% nitrogen and has a specific viscosity of 0.102.

Example 17 A solution of 31.5 grams of the fumarate ester of a mixture of C -C alcohols, 7.5 grams of N-vinyl oxazolidone, 1 gram of C -fiuoroalkyl acrylate and 0.2 gram of azodiisobutyronitrile in 40 grams of benzene is agitated under a nitrogen atmosphere in a 60 C. constant temperature bath for 18 hours. The terpolymer is precipitated in methanol, washed with methanol and dried.

Example 18 A solution of 30.3 grams of the fumarate ester of a 10 carbon alcohol derived from coconut oil, 9.7 grams of N-vinyl-S-methyl oxazolidone and 0.2 gram of azodiisobutyronitrile in 40 grams of benzene is agitated under a nitrogen atmosphere for 65 hours in a 60 C. constant temperature bath. The copolymer is precipitated in methanol, washed with methanol and dried.

Example 19 Thirty-six grams of decyl acrylate, 4 grams of N-vinyl- 5-methyl oxazolidone and 0.2 gram of azodiisobutyronitrile are dissolved in 40 grams of benzene and the solution is agitated under a nitrogen atmosphere for 65 hours in a 60 C. constant temperature bath. The copolymer is precipitated in methanol, washed with methanol and dried.

The intrinsic viscosity values reported above are obtained from a determination at 25 C. of the viscosity of a benzene solution of the polymer at a concentration of 0.1 gram per 100ml.

The interpolymers of this invention are often highly viscous liquids or amorphous solids. They are soluble in hydrocarbon oils and synthetic oils. When dissolved in these oils they are effective to improve the flow properties thereof in that they increase the viscosity index of the oil and/or lower the pour point of the oil.

The interpolymers have been found to be effective in many different types of lubricating oils. Oils derived from paraffinic and asphaltic crudes are benefited as well as all of the ordinarily available synthetic lubricants. These latter include the polyethers, polyesters, silicones, volatilized oils, etc. Ordinarily, the lubricating oils preferred will be fluid oils ranging in viscosity from about 40 Saybolt Universal seconds at 100 F. to about 200 Saybolt Universal seconds at 210 F.

The fuel oils include gasoline and the hydrocarbon oils suitable for use in a furnace burner or internal combustion engine, such as distillate and residual burner oils and diesel fuels having the following characteristics: minimum flash point, F.; maximum pour point, 70 F.; maximum 10% point, 650 F.; maximum Point, 900 F.; minimum API gravity, 2 4; and maximum viscosity at F., SUS (Saybolt Universal seconds). They may be derived from petroleum by a variety of methods including the straight distillation from crude petroleum oil and thermal or catalytic cracking of petroleum oil fractions.

The proportion of interpolymer to be used in a hydrocarbon oil for the purposes of this invention is at least about 0.000l%. The concentration in any particular instance depends largely upon the type of service to which the oil is to be subjected and the level of performance required for such service. As much as 10% by weight of the oil of the interpolymer may be required. For use in fuel oils only a very small amount need be used; the preferred amount, from about 0.001% to about 0.5%, is sufficient to provide effective detergent properties. In the case of lubricating oils on the other hand a larger amount is required, ranging from about 0.5% up to about and sometimes as high as Except for considerations of economy there generally is no disadvantage with the use 10 supernatant oil layer is characteristic of a poor detergent. The clarity of the supernatant oil layer was determined by the amount of light transmitted through the oil from a 3-volt, 0.75 watt incandescent bulb.

of more than these required amounts. 5 The hydrocarbon oils containing the interpolymers of this invention may contain other additive ingredients also. TABLE 11 Thus in the case of lubricating compositions these hydro- Lubricant Addition Agent Sediment Turbidity carbon oils may contain corrosion inhibitors such as zinc Sample (Ing.) dialkyl or di-(alkyl-phenyl) phosphorodithioates, alkyl 10 1 None Q3 Oleammnslumm phenols, phosphosulfurized terpenes; extreme pressure ad- 2 P du Example Heavy haleditives such as chlorinated parafiins and organic polysul- 221:: 283338; Egg; 2:: 31% gg: tides; other detergent materials such as alkaline earth 5 Product of Example 5.-." 0.0 Do. metal sulfonates, alkaline earth metal phenates and alka- 6 ggfgf Clem" line earth metal salts of fatty acids; and foam inhibiting y y xawlid havagents such as the dialkyl silicone polymers. gff

The effectiveness of the interpolymers of this invention as dispersing agents in fuel oils is shown by results obtained from the Oxygen Bomb Test. This test provides a t convenient means for the evaluation of deposit-forming The dispersant Pf p 0f the composltlons 0f thls tendencies of fuel oils underv conditions of accelerated invention y be Illustrated also y the results of an deterioration. In this test a 60 ml. sample of a fuel oil oxidation-dispercancy test which is useful as a screening normally susceptible to the deposition of degradation prodtest for determining the effectiveness .of the dispersant nets and containing the test additive, i placed in a bomb additive under light-duty service conditions. In this test (described in Test Procedure ASTM D52549). The a 350 ml. sample of a lubricating oil containing the addrpressure within the bomb is adjusted with oxygen to 100 tive to be tested is heated at 300 F. for 96 hours 111 lbs. per square inch and the bomb then placed in a con- 2" x 15" borosilicate tube. The lubricant base employed stant temperature bath at 100 C. for 48 hours. At the in the test is a Mid-Continent conventionally refined minconclusion of this period the sludge is weighed, the degree eral oil having a viscosity to about 200 Saybolt Universal of staining on the glass wall of the container noted, and seconds at 100 F. and containing 0.001% of iron naphthe appearance of the oil also noted (a light color indithenate (deterioration catalyst). Air is bubbled through eating a more effective dispersing agent than a darker the lubricant at a rate of 10 liters per hour. The oxidized color). sample is allowed to cool to 122 F., homogenized with TABLE I Fuel Oil Percent Sludge,

Sample Addition Agent Weight rug/(1)30 ml. Stain Color of Oil None 9. 5 Heavy. Black. Product of Example 1 0.007 0. 5 Trace Light tan. Product of Example 3 0.007 0.5 do Do. Product of Example 4 0.007 0. 5 do. Do.

It will be noted that the fuel oil samples containing 0.007% by weight of the products of Examples 1, 3 and 4 are superior, according to the above data, to the same fuel oil containing no such additive. The same fuel oil was used in each of the above four test samples.

The effectiveness of N-vinyl oxazolidone-alkyl acrylate interpolymers as detergents in mineral lubricating oils used in the crankcases of internal combustion engines is illustrated by the results summarized in Table II, obtained from the Drain Oil Detergency Test. In this test 6-cylinder 1958 Chevrolet cars (without oil filters) were operated for 50,000 miles as a fleet of taxicabs. In each case the crankcase lubricant was a solvent-refined Mid-Continent petroleum oil having a viscosity of 185 SUS/ 100 F. and a viscosity index of 112 and containing 5.9% by volume of a poly(alkyl methacrylate) viscosity index improver and 0.59% by volume of a zinc dialkyl phosphorodithioate (the alkyl groups comprising a mixture of butyl and amyl). Samples of each crankcase lubricant were taken at 3,000-mile intervals and the samples from each lubricant combined. A 30 ml. sample of the combined drains was mixed with 1% by weight of the additive being tested and 2% by weight of water. The mixture then was homogenized, placed in a graduated 100 ml., cone-shaped centrifuge tube and centrifuged for 2 hours at 1.500 rpm. The addition agents were evaluated in terms of the volume of deposited sediment and the turbidity of the supernatant oil layer. A minimum quantity of deposits plus a relatively hazy supernatant oil layer indicates an effective detergent whereas a large amount of deposits plus a clear TABLE III Additive Tested (1.5% by Oxidation-Dispersance Lubricant weight of diluent-free Test Result, mg. of

Sample chemical) deposit] 100 ml. of oil tested 1 N one 1, 000

Product of Example 13 7. 5 Product of Example 10 11. 4 Interpolymer prepared from 4. 1

an (:15) w. mixture of decyl methacrylate and N-vinyl oxazolidone.

The efiFect upon the viscosity characteristics of a hydrocarbon oil of the interpolymers described herein is shown by the data of Table IV. The oil base of each of the 13 lubricant samples was the same SAE 20 mineral oil having a viscosity of 46.5 SUS/210" F. and a viscosity index of 95. Lubricant samples Nos. 213 contain 1.5% by weight of the indicated addition agents.

TAB LE IV Lubricant Viscosity at 210 Viscosity Sample Addition Agent (Saybolt Universal Index seconds) None 46. 95 Product of Example 8.. 5 6 129 Product of Example l 53. 9 132 Product of Example 7.- 51. 5 131 Product of Example 9 58. 6 121 Product of Example 2.. 56.0 130 Product of Example 5 57. 5 131 Product of Example 2.. 58. 6 131 Product of Example 76. 2 147 Product of Example 13 69. 5 147 Product of Example l8 55. 4 135 Product of Example 19. 59. 6 142 Product of Example 20. 68. 6 142 Specific examples of hydrocarbon oil compositions containing the polymeric addition agents are as follows (all percentages by weight):

Percent SAE l0W-3O lubricating oil 97.5 Product of Example 1 1.5 Zinc di-cyclohexyl phosphorodithioate 1 Catalytically cracked No. 2 light fuel oil 99.95 Product of Example 4 0.05

The polymeric additives described above are similarly useful in synthetic lubricants, e.g., polyethers such as a polypropylene oxide having an average molecular weight of 2000, polyesters such as di-(Z-ethylhexyl sebacate), silicones such as a dimethyl siloxane having an average molecular weight of 800, volatilized oils such as volatilized sperm oil, and chlorinated compounds such as monochloronaphthalene.

All amounts, not otherwise designated herein, are parts by weight.

What is claimed is:

1. A composition comprising a major proportion of an oilselected from the class consisting of fuel oils and lubricating oils and at least 0.000l% by weight of an interpolymer having monomeric units of from about 5 to about parts by weight of an N-vinyl oxazolidone and from about 100 to about 75 parts by weight of at least one oil-solubilizing vinyl co-monomer selected from the group consisting of alkyl esters of unsaturated lower aliphatic carboxylic acids having from about 4 to about carbon atoms in the alkyl group, l-olefins containing from about 8 to about 20 carbon atoms, vinyl esters of higher fatty acids and N-alkyl acrylamides having from about 7 to about 15 carbon atoms in the alkyl group.

2. The composition of claim 1 characterized further in that the N-vinyl oxazolidone has the structure wherein R is selected from the group consisting of hydrogen and a lower alkyl group and R and R are radicals having fewer than seven carbon atoms and are selected from the group consisting of hydrogen, phenyl, chloroalkyl and alkyl.

3. The composition of claim 1 characterized further in that the N-vinyl oxazolidone is unsubstituted.

*4. The composition of claim 2 characterized further in that R is a lower alkyl.

5.. The composition of claim 2 characterized further in that R is methyl and R is hydrogen.

6. The composition of claim 2 characterized further in that R is hydrogen, R is methyl and R is hydrogen.

7. The composition of claim 1 characterized further in that the interpolymer contains two oil-solubilizing vinyl co-monorners.

8. The composition of claim 1 characterized further in that at least one of the oil solubilizing vinyl co-monomers is an alkyl acrylate in which the alkyl group contains from about 8 to about 30 carbon atoms and the acrylic radical contains from 3 to about 6 carbon atoms.

9. The composition of claim 8 characterized further in that the alkyl acrylate is decyl acrylate or methacrylate.

10. The composition of claim 1 characterized further in that at least one of the oil solubilizing vinyl co-monorners is a dialkyl ester of an cap-unsaturated dicarboxylic acid in which each alkyl group contains from about 4 to about 20 carbon atoms and the acid contains from 4 to 5 carbon atoms.

11. The composition of claim 10 characterized further in that the dialkyl ester of an a,,8-unsaturated dicarboxylic acid is a dialkyl fumarate.

12. The composition of claim 10 characterized further in that the dialkyl ester of an a e-unsaturated dicarboxylic acid is a dialkyl itaconate.

13. The composition of claim 1 characterized further in that the interpolymer contains (a) an N-vinyl oxazolidone, (b) an oil solubilizing vinyl comonomer selected from the class consisting of alkyl acrylates, alkyl methacrylates, dialkyl fumarates and dialkyl itaconates, the alkyl group of each said comonomer containing from about 8 to about 30 carbon atoms, and (c) a vinyl comonomer selected from the class consisting of vinyl esters of fatty acids, l-olefins, N-alkyl acryl amides, c p-unsaturated aliphatic nitriles, alkyl vinyl ethers, fiuoroalkyl acrylates, and fluoroalkyl methacrylates; wherein the relative amounts by weight of (a), (b), and (c) are from about 5 to about 25 parts of (a), from about 100 to about 75 parts of (b) and up to about 100 parts of (c).

14. A composition comprising a major proportion of an oil selected from the class consisting of fuel oils and lubricating oils and a minor proportion, sufiicient to inhibit the deposition of degradation products, of an interpolymer having an intrinsic viscosity of from about 0.1 to about 3.0, said interpolymer having monomeric units of from about 5 to about 25 parts by weight of an N-vinyl oxazolidone having the structure RzCH-CHRa wherein R is selected from the group consisting of hydrogen and a lower alkyl group and R and R are radicals having fewer than seven carbon atoms, selected from the group consisting of hydrogen, phenyl, chloroalkyl and alkyl, and from about 75 to about 95 parts by weight of an alkyl acrylate in which said alkyl group contains from about eight to about thirty carbon atoms and the acrylic radical contains from 3 to about 6 carbon atoms.

15. A composition comprising a major proportion of hydrocarbon material selected from the group consisting of fuel oils and lubricating oils and a minor proportion, sufficient to inhibit the deposition of degradation prodnets, of an interpolymer having an intrinsic viscosity of from about 0.1 to about 3.0, said interpolymer having monomeric units of from about 5 to about 25 parts of N-vinyl oxazolidone and from about 75 to about 95 parts of an alkyl acrylate in which said alkyl group contains from about eight to about thirty carbon atoms and the acrylic radical contains from 3 to about 6 carbon atoms.

16. A composition comprising a major proportion of hydrocarbon material selected from the group consisting of fuel oils and lubricating oils and a minor proportion, sufiicient to inhibit the deposition of degradation prodnets, of a copolymer containing about 15 parts by weight of N-vinyl oxazolidone and about parts by weight of decyl methacrylate.

17. A composition comprising a major proportion of hydrocarbon material selected from the group consisting of fuel oils and lubricating oils and a minor proportion; suflicient to inhibit the deposition of degradation products, of a terpolymer containing about 15 parts by Weight of N-vinyl oxazolidone, about 63 parts by Weight of a mixed dialkyl fumarate in which each alkyl group has from 12 to 14 carbon atoms, and about 2 parts of tetrafluoroamyl acryla-te.

18. A composition comprising a major proportion of hydrocarbon material selected from the group consisting of fuel oils and lubricating oils and a minor proportion sufficient to inhibit the deposition of degradation products, of a copolymer containing about 10 parts of N-vinyl- S-methyl-oxazolidone and about 90 parts of decyl acrylate.

19. A composition comprising a major proportion of hydrocarbon material selected from the group consisting of fuel oils and lubricating oils and a minor proportion, sufiicient to inhibit the deposition of degradation prodnets, of a copolymer containing about 10 parts of N-vinyl- S-methyl-oxazolidone and about 90- parts of di-decyl fumarate.

References Cited UNITED STATES PATENTS 2,818,362 12/1957 Drechsel 260-88.3 XR 2,966,496 12/1960 Arend et a1 26088.3 XR 3,030,339 4/1962 Tousignant et al. 2608 8.3 XR

FOREIGN PATENTS 226,954 2/ l960 Australia. 808,665 2/ 1959 Great Britain. 822,620 -10/ 1959 Great Britain.

DANIEL E. WYMAN, Primary Examiner.

PATRICK P. GARVIN, Examiner. 

